The Hitler comedy ‘Jojo Rabbit’ is actually a love letter to single mothers, including Taika Waititi’s

"Thor: Ragnarok" director Taika Waititi's latest movie "Jojo Rabbit" is a World War II-set satire in which he portrays Adolf Hitler. But the film is also "a love letter to mothers, especially solo mothers," he explained after its world-premiere screening Sunday night at the Toronto International Film Festival.

Out Oct. 18, the Fox Searchlight title centers on a young German boy (newcomer Roman Griffin Davis) who discovers a Jewish girl (Thomasin McKenzie) hiding in his home. Scarlett Johansson, Sam Rockwell, Rebel Wilson, Stephen Merchant and Alfie Allen are among the cast.

"I grew up with a single mom," Waititi told the audience, who gave lengthy applause for Davis and McKenzie. "I didn't realize until I had my own children that she would've done anything for me, and she did."

Johansson plays the mother of the young boy. "(Her) character, for me, is the most important element in the entire film, and probably the only grounded character," he added. "She's a clown, but she's trying to save her kid."

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Waititi thanked his mother while introducing the film because it was because of her that he first encountered the source material. She was reading Christina Leunens' book "Caging Skies," and recommended it to him with so much enthusiasm.

"The way she described it, I thought, 'What a great film idea!' Then I read the book, and it is an incredible, very good book, but it wasn't exactly like my mom described it," he said to the audience's laughter.

Waititi then wrote a script that's closer to his mother's version of the book, and added in humor via the boy's imaginary friend, Adolf Hitler. "Growing up, I've often fantasized about father figures and wanting that kind of presence in my life," he said. "I think it's no different for a boy growing up with a solo mother in Germany: 'I want a dad, but also my idol is this buffoon.'

"It's essentially the core of a young boy who has been indoctrinated and has to understand and befriend (someone)," added the writer-director. "The idea was kind of like having a monster in the attic, but it's just a human."

To portray that human, McKenzie (who delivered a breakout performance in the indie "Leave No Trace") had initially done quite a bit of research and reflection, but Waititi instructed her to forget it all and watch movies like "Heathers" and "Mean Girls" instead. The actress explained this strategy: "She had a life before this disgusting tragedy happened to her, and I think it was important to present her as a figure of hope, and that she is a strong, brave, very staunch girl."

As for a Nazi officer indoctrinating the Hitler youth, Rockwell explained his method for getting into character. "I thought, if Bill Murray was a disillusioned Nazi, that's how I was gonna play it," he joked. "I think Taika liked that idea!"

Waititi acknowledged that he did, and joked, "But sadly, Bill was unavailable."